What type of line is used for continuous water supply in firefighting?

In firefighting, the concept of a "regular line" typically refers to a hose line that is established to ensure a continuous supply of water to support firefighting operations. This line is critical for maintaining water flow during firefighting efforts, especially in situations where sustained suppression is necessary.

In contrast, other lines such as backup lines are used to provide additional support and ensure safety, while attack lines are specifically employed to directly combat flames and attack the fire. The term "primary line" may suggest a main line for specific operations, but it does not necessarily imply the continuous water supply concept that the "regular line" encapsulates. Therefore, a regular line is the most appropriate choice when referring to continuous water supply within the context of firefighting procedures.